Tyranny, tyranny, tyranny. It seems to echo from every direction like old church bells. Newspapers headline it, broadcasters auto-cue it, and party-goers celebrate the end of it - and they are right to. In his statement on Muammar al-Gaddafi's killing, Barack Obama said "the dark shadow of tyranny has been lifted". Now there's a sound-bite.

As thousands discharged weapons into the air with gleeful smiles, it was easy to be swept up in the triumphalism of the moment. As Brutus said, "then walk we forth even to the marketplace, and, waving our red weapons o'er our heads, let's all cry out 'peace, freedom, and liberty!'"